1. Field of the Invention
The present invention relates to a shutter apparatus and an image-pickup apparatus having the shutter apparatus.
2. Description of the Related Art
A conventional shutter apparatus rotatably holds blade group divided into a plurality of blades by two arms, and forms a parallel link. The blade group is connected with a blade driving member having a drive spring for blade travelling and an armature electrically attached to a holding electric magnet. In the state of preparation for taking, the armature is abutted against yoke adsorption surface of the holding electric magnet by a charge lever or a charge cam gear so as to hold the blade group.
After release, the charge lever or the charge cam gear evacuates from a blade group holding position, and the blade group is held at a start position by magnetic force of the energized holding magnetic. And imaging operation is operated by a slit exposure using a leading blade group and a trailing blade group or an exposure using an electronic shutter and a trailing blade group when cutting energization of the holding magnet.
After travelling of the blade group, the driving spring is charged by the charge lever or the charge cam gear, and the blade group moves to the position of preparation for taking and waits for next shooting.
In the state of preparation for taking, the blade driving member need to be overcharged so that the armature can certainly abut against the yoke adsorption surface. Generally, overcharge is to further charge the driving spring from the state where the armature abuts against the yoke adsorption surface. In Japanese Patent No. 3990831, a blade driving member has a roller abutting against a charge lever, and overcharge amount of the blade driving member is adjusted by the roller. In other words, the operational amount of the charge lever or a charge cam gear in charge operation is adjusted.
However, in Japanese Patent No. 3990831, a retaining member retaining the roller is needed, and the retaining member needs to dismount the retaining when exchanging the roller. Therefore, there is a problem that exchanging of the roller is troublesome.
Moreover, the roller is generally a metal, and is arranged at a position left from the rotating center of the blade driving member. Therefore, there are problems that inertia of the blade driving member is widely affected, travelling characteristics of the blade driving member is changed by size of the roller, and each travelling characteristics (exposure characteristics) of the shutter apparatus is different.
Additionally, in Japanese Patent Laid-Open No. 2003-315872, a blade room where a blade group travels is provided on an image-pickup element side of a shutter base plate, and a blade driving member and a set member are provided on the opposite side. A through-hole is formed on the shutter base plate, and a blade driving member is inserted into a blade arm via the through-hole.
However, in Japanese Patent Laid-Open No. 2003-315872, attachment error is generated since the rotating axis of the blade arm and the rotating axis of the blade driving member are provided on separate surface of the shutter base plate.
In addition, travel sliding load of the blade group increases and the shutter accuracy degrades by travel sliding load since the blade group fits the rotating axis of the blade arm and the rotating axis of the blade driving member, and slides them.
Moreover, the apparatus enlarges since the surface of the shutter base plate exists between the blade room and the set member